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Diffstat (limited to 'chromium/mojo/system/core.cc')
| -rw-r--r-- | chromium/mojo/system/core.cc | 561 |
1 files changed, 561 insertions, 0 deletions
diff --git a/chromium/mojo/system/core.cc b/chromium/mojo/system/core.cc new file mode 100644 index 00000000000..d72198f1610 --- /dev/null +++ b/chromium/mojo/system/core.cc @@ -0,0 +1,561 @@ +// Copyright 2013 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#include "mojo/system/core.h" + +#include <vector> + +#include "base/logging.h" +#include "base/time/time.h" +#include "mojo/public/c/system/macros.h" +#include "mojo/system/constants.h" +#include "mojo/system/data_pipe.h" +#include "mojo/system/data_pipe_consumer_dispatcher.h" +#include "mojo/system/data_pipe_producer_dispatcher.h" +#include "mojo/system/dispatcher.h" +#include "mojo/system/local_data_pipe.h" +#include "mojo/system/memory.h" +#include "mojo/system/message_pipe.h" +#include "mojo/system/message_pipe_dispatcher.h" +#include "mojo/system/raw_shared_buffer.h" +#include "mojo/system/shared_buffer_dispatcher.h" +#include "mojo/system/waiter.h" + +namespace mojo { +namespace system { + +// Implementation notes +// +// Mojo primitives are implemented by the singleton |Core| object. Most calls +// are for a "primary" handle (the first argument). |Core::GetDispatcher()| is +// used to look up a |Dispatcher| object for a given handle. That object +// implements most primitives for that object. The wait primitives are not +// attached to objects and are implemented by |Core| itself. +// +// Some objects have multiple handles associated to them, e.g., message pipes +// (which have two). In such a case, there is still a |Dispatcher| (e.g., +// |MessagePipeDispatcher|) for each handle, with each handle having a strong +// reference to the common "secondary" object (e.g., |MessagePipe|). This +// secondary object does NOT have any references to the |Dispatcher|s (even if +// it did, it wouldn't be able to do anything with them due to lock order +// requirements -- see below). +// +// Waiting is implemented by having the thread that wants to wait call the +// |Dispatcher|s for the handles that it wants to wait on with a |Waiter| +// object; this |Waiter| object may be created on the stack of that thread or be +// kept in thread local storage for that thread (TODO(vtl): future improvement). +// The |Dispatcher| then adds the |Waiter| to a |WaiterList| that's either owned +// by that |Dispatcher| (see |SimpleDispatcher|) or by a secondary object (e.g., +// |MessagePipe|). To signal/wake a |Waiter|, the object in question -- either a +// |SimpleDispatcher| or a secondary object -- talks to its |WaiterList|. + +// Thread-safety notes +// +// Mojo primitives calls are thread-safe. We achieve this with relatively +// fine-grained locking. There is a global handle table lock. This lock should +// be held as briefly as possible (TODO(vtl): a future improvement would be to +// switch it to a reader-writer lock). Each |Dispatcher| object then has a lock +// (which subclasses can use to protect their data). +// +// The lock ordering is as follows: +// 1. global handle table lock, global mapping table lock +// 2. |Dispatcher| locks +// 3. secondary object locks +// ... +// INF. |Waiter| locks +// +// Notes: +// - While holding a |Dispatcher| lock, you may not unconditionally attempt +// to take another |Dispatcher| lock. (This has consequences on the +// concurrency semantics of |MojoWriteMessage()| when passing handles.) +// Doing so would lead to deadlock. +// - Locks at the "INF" level may not have any locks taken while they are +// held. + +Core::Core() { +} + +Core::~Core() { +} + +MojoHandle Core::AddDispatcher( + const scoped_refptr<Dispatcher>& dispatcher) { + base::AutoLock locker(handle_table_lock_); + return handle_table_.AddDispatcher(dispatcher); +} + +scoped_refptr<Dispatcher> Core::GetDispatcher(MojoHandle handle) { + if (handle == MOJO_HANDLE_INVALID) + return NULL; + + base::AutoLock locker(handle_table_lock_); + return handle_table_.GetDispatcher(handle); +} + +MojoTimeTicks Core::GetTimeTicksNow() { + return base::TimeTicks::Now().ToInternalValue(); +} + +MojoResult Core::Close(MojoHandle handle) { + if (handle == MOJO_HANDLE_INVALID) + return MOJO_RESULT_INVALID_ARGUMENT; + + scoped_refptr<Dispatcher> dispatcher; + { + base::AutoLock locker(handle_table_lock_); + MojoResult result = handle_table_.GetAndRemoveDispatcher(handle, + &dispatcher); + if (result != MOJO_RESULT_OK) + return result; + } + + // The dispatcher doesn't have a say in being closed, but gets notified of it. + // Note: This is done outside of |handle_table_lock_|. As a result, there's a + // race condition that the dispatcher must handle; see the comment in + // |Dispatcher| in dispatcher.h. + return dispatcher->Close(); +} + +MojoResult Core::Wait(MojoHandle handle, + MojoHandleSignals signals, + MojoDeadline deadline) { + return WaitManyInternal(&handle, &signals, 1, deadline); +} + +MojoResult Core::WaitMany(const MojoHandle* handles, + const MojoHandleSignals* signals, + uint32_t num_handles, + MojoDeadline deadline) { + if (!VerifyUserPointerWithCount<MojoHandle>(handles, num_handles)) + return MOJO_RESULT_INVALID_ARGUMENT; + if (!VerifyUserPointerWithCount<MojoHandleSignals>(signals, num_handles)) + return MOJO_RESULT_INVALID_ARGUMENT; + if (num_handles < 1) + return MOJO_RESULT_INVALID_ARGUMENT; + if (num_handles > kMaxWaitManyNumHandles) + return MOJO_RESULT_RESOURCE_EXHAUSTED; + return WaitManyInternal(handles, signals, num_handles, deadline); +} + +MojoResult Core::CreateMessagePipe(const MojoCreateMessagePipeOptions* options, + MojoHandle* message_pipe_handle0, + MojoHandle* message_pipe_handle1) { + MojoCreateMessagePipeOptions validated_options = {}; + // This will verify the |options| pointer. + MojoResult result = MessagePipeDispatcher::ValidateCreateOptions( + options, &validated_options); + if (result != MOJO_RESULT_OK) + return result; + if (!VerifyUserPointer<MojoHandle>(message_pipe_handle0)) + return MOJO_RESULT_INVALID_ARGUMENT; + if (!VerifyUserPointer<MojoHandle>(message_pipe_handle1)) + return MOJO_RESULT_INVALID_ARGUMENT; + + scoped_refptr<MessagePipeDispatcher> dispatcher0( + new MessagePipeDispatcher(validated_options)); + scoped_refptr<MessagePipeDispatcher> dispatcher1( + new MessagePipeDispatcher(validated_options)); + + std::pair<MojoHandle, MojoHandle> handle_pair; + { + base::AutoLock locker(handle_table_lock_); + handle_pair = handle_table_.AddDispatcherPair(dispatcher0, dispatcher1); + } + if (handle_pair.first == MOJO_HANDLE_INVALID) { + DCHECK_EQ(handle_pair.second, MOJO_HANDLE_INVALID); + LOG(ERROR) << "Handle table full"; + dispatcher0->Close(); + dispatcher1->Close(); + return MOJO_RESULT_RESOURCE_EXHAUSTED; + } + + scoped_refptr<MessagePipe> message_pipe(new MessagePipe()); + dispatcher0->Init(message_pipe, 0); + dispatcher1->Init(message_pipe, 1); + + *message_pipe_handle0 = handle_pair.first; + *message_pipe_handle1 = handle_pair.second; + return MOJO_RESULT_OK; +} + +// Implementation note: To properly cancel waiters and avoid other races, this +// does not transfer dispatchers from one handle to another, even when sending a +// message in-process. Instead, it must transfer the "contents" of the +// dispatcher to a new dispatcher, and then close the old dispatcher. If this +// isn't done, in the in-process case, calls on the old handle may complete +// after the the message has been received and a new handle created (and +// possibly even after calls have been made on the new handle). +MojoResult Core::WriteMessage(MojoHandle message_pipe_handle, + const void* bytes, + uint32_t num_bytes, + const MojoHandle* handles, + uint32_t num_handles, + MojoWriteMessageFlags flags) { + scoped_refptr<Dispatcher> dispatcher(GetDispatcher(message_pipe_handle)); + if (!dispatcher) + return MOJO_RESULT_INVALID_ARGUMENT; + + // Easy case: not sending any handles. + if (num_handles == 0) + return dispatcher->WriteMessage(bytes, num_bytes, NULL, flags); + + // We have to handle |handles| here, since we have to mark them busy in the + // global handle table. We can't delegate this to the dispatcher, since the + // handle table lock must be acquired before the dispatcher lock. + // + // (This leads to an oddity: |handles|/|num_handles| are always verified for + // validity, even for dispatchers that don't support |WriteMessage()| and will + // simply return failure unconditionally. It also breaks the usual + // left-to-right verification order of arguments.) + if (!VerifyUserPointerWithCount<MojoHandle>(handles, num_handles)) + return MOJO_RESULT_INVALID_ARGUMENT; + if (num_handles > kMaxMessageNumHandles) + return MOJO_RESULT_RESOURCE_EXHAUSTED; + + // We'll need to hold on to the dispatchers so that we can pass them on to + // |WriteMessage()| and also so that we can unlock their locks afterwards + // without accessing the handle table. These can be dumb pointers, since their + // entries in the handle table won't get removed (since they'll be marked as + // busy). + std::vector<DispatcherTransport> transports(num_handles); + + // When we pass handles, we have to try to take all their dispatchers' locks + // and mark the handles as busy. If the call succeeds, we then remove the + // handles from the handle table. + { + base::AutoLock locker(handle_table_lock_); + MojoResult result = handle_table_.MarkBusyAndStartTransport( + message_pipe_handle, handles, num_handles, &transports); + if (result != MOJO_RESULT_OK) + return result; + } + + MojoResult rv = dispatcher->WriteMessage(bytes, num_bytes, &transports, + flags); + + // We need to release the dispatcher locks before we take the handle table + // lock. + for (uint32_t i = 0; i < num_handles; i++) + transports[i].End(); + + { + base::AutoLock locker(handle_table_lock_); + if (rv == MOJO_RESULT_OK) + handle_table_.RemoveBusyHandles(handles, num_handles); + else + handle_table_.RestoreBusyHandles(handles, num_handles); + } + + return rv; +} + +MojoResult Core::ReadMessage(MojoHandle message_pipe_handle, + void* bytes, + uint32_t* num_bytes, + MojoHandle* handles, + uint32_t* num_handles, + MojoReadMessageFlags flags) { + scoped_refptr<Dispatcher> dispatcher(GetDispatcher(message_pipe_handle)); + if (!dispatcher) + return MOJO_RESULT_INVALID_ARGUMENT; + + if (num_handles) { + if (!VerifyUserPointer<uint32_t>(num_handles)) + return MOJO_RESULT_INVALID_ARGUMENT; + if (!VerifyUserPointerWithCount<MojoHandle>(handles, *num_handles)) + return MOJO_RESULT_INVALID_ARGUMENT; + } + + // Easy case: won't receive any handles. + if (!num_handles || *num_handles == 0) + return dispatcher->ReadMessage(bytes, num_bytes, NULL, num_handles, flags); + + DispatcherVector dispatchers; + MojoResult rv = dispatcher->ReadMessage(bytes, num_bytes, + &dispatchers, num_handles, + flags); + if (!dispatchers.empty()) { + DCHECK_EQ(rv, MOJO_RESULT_OK); + DCHECK(num_handles); + DCHECK_LE(dispatchers.size(), static_cast<size_t>(*num_handles)); + + bool success; + { + base::AutoLock locker(handle_table_lock_); + success = handle_table_.AddDispatcherVector(dispatchers, handles); + } + if (!success) { + LOG(ERROR) << "Received message with " << dispatchers.size() + << " handles, but handle table full"; + // Close dispatchers (outside the lock). + for (size_t i = 0; i < dispatchers.size(); i++) { + if (dispatchers[i]) + dispatchers[i]->Close(); + } + } + } + + return rv; +} + +MojoResult Core::CreateDataPipe(const MojoCreateDataPipeOptions* options, + MojoHandle* data_pipe_producer_handle, + MojoHandle* data_pipe_consumer_handle) { + MojoCreateDataPipeOptions validated_options = {}; + // This will verify the |options| pointer. + MojoResult result = DataPipe::ValidateCreateOptions(options, + &validated_options); + if (result != MOJO_RESULT_OK) + return result; + if (!VerifyUserPointer<MojoHandle>(data_pipe_producer_handle)) + return MOJO_RESULT_INVALID_ARGUMENT; + if (!VerifyUserPointer<MojoHandle>(data_pipe_consumer_handle)) + return MOJO_RESULT_INVALID_ARGUMENT; + + scoped_refptr<DataPipeProducerDispatcher> producer_dispatcher( + new DataPipeProducerDispatcher()); + scoped_refptr<DataPipeConsumerDispatcher> consumer_dispatcher( + new DataPipeConsumerDispatcher()); + + std::pair<MojoHandle, MojoHandle> handle_pair; + { + base::AutoLock locker(handle_table_lock_); + handle_pair = handle_table_.AddDispatcherPair(producer_dispatcher, + consumer_dispatcher); + } + if (handle_pair.first == MOJO_HANDLE_INVALID) { + DCHECK_EQ(handle_pair.second, MOJO_HANDLE_INVALID); + LOG(ERROR) << "Handle table full"; + producer_dispatcher->Close(); + consumer_dispatcher->Close(); + return MOJO_RESULT_RESOURCE_EXHAUSTED; + } + DCHECK_NE(handle_pair.second, MOJO_HANDLE_INVALID); + + scoped_refptr<DataPipe> data_pipe(new LocalDataPipe(validated_options)); + producer_dispatcher->Init(data_pipe); + consumer_dispatcher->Init(data_pipe); + + *data_pipe_producer_handle = handle_pair.first; + *data_pipe_consumer_handle = handle_pair.second; + return MOJO_RESULT_OK; +} + +MojoResult Core::WriteData(MojoHandle data_pipe_producer_handle, + const void* elements, + uint32_t* num_bytes, + MojoWriteDataFlags flags) { + scoped_refptr<Dispatcher> dispatcher( + GetDispatcher(data_pipe_producer_handle)); + if (!dispatcher) + return MOJO_RESULT_INVALID_ARGUMENT; + + return dispatcher->WriteData(elements, num_bytes, flags); +} + +MojoResult Core::BeginWriteData(MojoHandle data_pipe_producer_handle, + void** buffer, + uint32_t* buffer_num_bytes, + MojoWriteDataFlags flags) { + scoped_refptr<Dispatcher> dispatcher( + GetDispatcher(data_pipe_producer_handle)); + if (!dispatcher) + return MOJO_RESULT_INVALID_ARGUMENT; + + return dispatcher->BeginWriteData(buffer, buffer_num_bytes, flags); +} + +MojoResult Core::EndWriteData(MojoHandle data_pipe_producer_handle, + uint32_t num_bytes_written) { + scoped_refptr<Dispatcher> dispatcher( + GetDispatcher(data_pipe_producer_handle)); + if (!dispatcher) + return MOJO_RESULT_INVALID_ARGUMENT; + + return dispatcher->EndWriteData(num_bytes_written); +} + +MojoResult Core::ReadData(MojoHandle data_pipe_consumer_handle, + void* elements, + uint32_t* num_bytes, + MojoReadDataFlags flags) { + scoped_refptr<Dispatcher> dispatcher( + GetDispatcher(data_pipe_consumer_handle)); + if (!dispatcher) + return MOJO_RESULT_INVALID_ARGUMENT; + + return dispatcher->ReadData(elements, num_bytes, flags); +} + +MojoResult Core::BeginReadData(MojoHandle data_pipe_consumer_handle, + const void** buffer, + uint32_t* buffer_num_bytes, + MojoReadDataFlags flags) { + scoped_refptr<Dispatcher> dispatcher( + GetDispatcher(data_pipe_consumer_handle)); + if (!dispatcher) + return MOJO_RESULT_INVALID_ARGUMENT; + + return dispatcher->BeginReadData(buffer, buffer_num_bytes, flags); +} + +MojoResult Core::EndReadData(MojoHandle data_pipe_consumer_handle, + uint32_t num_bytes_read) { + scoped_refptr<Dispatcher> dispatcher( + GetDispatcher(data_pipe_consumer_handle)); + if (!dispatcher) + return MOJO_RESULT_INVALID_ARGUMENT; + + return dispatcher->EndReadData(num_bytes_read); +} + +MojoResult Core::CreateSharedBuffer( + const MojoCreateSharedBufferOptions* options, + uint64_t num_bytes, + MojoHandle* shared_buffer_handle) { + MojoCreateSharedBufferOptions validated_options = {}; + // This will verify the |options| pointer. + MojoResult result = + SharedBufferDispatcher::ValidateCreateOptions(options, + &validated_options); + if (result != MOJO_RESULT_OK) + return result; + if (!VerifyUserPointer<MojoHandle>(shared_buffer_handle)) + return MOJO_RESULT_INVALID_ARGUMENT; + + scoped_refptr<SharedBufferDispatcher> dispatcher; + result = SharedBufferDispatcher::Create(validated_options, num_bytes, + &dispatcher); + if (result != MOJO_RESULT_OK) { + DCHECK(!dispatcher); + return result; + } + + MojoHandle h = AddDispatcher(dispatcher); + if (h == MOJO_HANDLE_INVALID) { + LOG(ERROR) << "Handle table full"; + dispatcher->Close(); + return MOJO_RESULT_RESOURCE_EXHAUSTED; + } + + *shared_buffer_handle = h; + return MOJO_RESULT_OK; +} + +MojoResult Core::DuplicateBufferHandle( + MojoHandle buffer_handle, + const MojoDuplicateBufferHandleOptions* options, + MojoHandle* new_buffer_handle) { + scoped_refptr<Dispatcher> dispatcher(GetDispatcher(buffer_handle)); + if (!dispatcher) + return MOJO_RESULT_INVALID_ARGUMENT; + + // Don't verify |options| here; that's the dispatcher's job. + if (!VerifyUserPointer<MojoHandle>(new_buffer_handle)) + return MOJO_RESULT_INVALID_ARGUMENT; + + scoped_refptr<Dispatcher> new_dispatcher; + MojoResult result = dispatcher->DuplicateBufferHandle(options, + &new_dispatcher); + if (result != MOJO_RESULT_OK) + return result; + + MojoHandle new_handle = AddDispatcher(new_dispatcher); + if (new_handle == MOJO_HANDLE_INVALID) { + LOG(ERROR) << "Handle table full"; + dispatcher->Close(); + return MOJO_RESULT_RESOURCE_EXHAUSTED; + } + + *new_buffer_handle = new_handle; + return MOJO_RESULT_OK; +} + +MojoResult Core::MapBuffer(MojoHandle buffer_handle, + uint64_t offset, + uint64_t num_bytes, + void** buffer, + MojoMapBufferFlags flags) { + scoped_refptr<Dispatcher> dispatcher(GetDispatcher(buffer_handle)); + if (!dispatcher) + return MOJO_RESULT_INVALID_ARGUMENT; + + if (!VerifyUserPointerWithCount<void*>(buffer, 1)) + return MOJO_RESULT_INVALID_ARGUMENT; + + scoped_ptr<RawSharedBufferMapping> mapping; + MojoResult result = dispatcher->MapBuffer(offset, num_bytes, flags, &mapping); + if (result != MOJO_RESULT_OK) + return result; + + DCHECK(mapping); + void* address = mapping->base(); + { + base::AutoLock locker(mapping_table_lock_); + result = mapping_table_.AddMapping(mapping.Pass()); + } + if (result != MOJO_RESULT_OK) + return result; + + *buffer = address; + return MOJO_RESULT_OK; +} + +MojoResult Core::UnmapBuffer(void* buffer) { + base::AutoLock locker(mapping_table_lock_); + return mapping_table_.RemoveMapping(buffer); +} + +// Note: We allow |handles| to repeat the same handle multiple times, since +// different flags may be specified. +// TODO(vtl): This incurs a performance cost in |RemoveWaiter()|. Analyze this +// more carefully and address it if necessary. +MojoResult Core::WaitManyInternal(const MojoHandle* handles, + const MojoHandleSignals* signals, + uint32_t num_handles, + MojoDeadline deadline) { + DCHECK_GT(num_handles, 0u); + + DispatcherVector dispatchers; + dispatchers.reserve(num_handles); + for (uint32_t i = 0; i < num_handles; i++) { + scoped_refptr<Dispatcher> dispatcher = GetDispatcher(handles[i]); + if (!dispatcher) + return MOJO_RESULT_INVALID_ARGUMENT; + dispatchers.push_back(dispatcher); + } + + // TODO(vtl): Should make the waiter live (permanently) in TLS. + Waiter waiter; + waiter.Init(); + + uint32_t i; + MojoResult rv = MOJO_RESULT_OK; + for (i = 0; i < num_handles; i++) { + rv = dispatchers[i]->AddWaiter(&waiter, signals[i], i); + if (rv != MOJO_RESULT_OK) + break; + } + uint32_t num_added = i; + + if (rv == MOJO_RESULT_ALREADY_EXISTS) { + rv = static_cast<MojoResult>(i); // The i-th one is already "triggered". + } else if (rv == MOJO_RESULT_OK) { + uint32_t context = static_cast<uint32_t>(-1); + rv = waiter.Wait(deadline, &context); + if (rv == MOJO_RESULT_OK) + rv = static_cast<MojoResult>(context); + } + + // Make sure no other dispatchers try to wake |waiter| for the current + // |Wait()|/|WaitMany()| call. (Only after doing this can |waiter| be + // destroyed, but this would still be required if the waiter were in TLS.) + for (i = 0; i < num_added; i++) + dispatchers[i]->RemoveWaiter(&waiter); + + return rv; +} + +} // namespace system +} // namespace mojo |